<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        div {
            width: 200px;
            height: 200px;
            background-color: pink;
            border: 1px solid green;
            float: left;
            margin-left: 20px;
            text-align: center;
            line-height: 200px;
        }
        /* 单值法： */
        .box2 {
            border-radius: 50px;
        }
        /* 四值法 */
        .box3 {
            border-radius: 30px 60px 90px 120px;
        }
        /* 拆分法 */
        .box4 {
            /* 左上 */
            border-top-left-radius: 20px;
            /* 右上 */
            border-top-right-radius: 40px;
            /* 左下 */
            border-bottom-left-radius: 60px;
            /* 右下 */
            border-bottom-right-radius: 80px;
        }
        /* 百分比法 */
        .box5 {
            border-radius: 50%;
        }
    </style>
</head>
<body>
    <div class="box1">box1</div>
    <div class="box2">box2</div>
    <div class="box3">box3</div>
    <div class="box4">box4</div>
    <div class="box5">box5</div>
</body>
</html>